Fluid pump



S pt- 0, 1968 H. TRAMPOSCH FLUID PUMP 2 Sheets-Sheet 1 Filed Oct. 17, 1966 IN v :NTOR.

rn oosc/z 477'0RNEY 6/ Herbert Sept. 10, 1968 H. TRAMPOSCH FLUID PUMP 2 Sheets-Sheet 2 Filed Oct. 17. 19%

k P Em r hm) m 0 w m v WM \lv m 0/ W. wk W m W m w mm W mm ,W 4 s NR \v R R m w v M Y m M...) A mm United States Patent 3,400,883 FLUID PUMP Herbert Tramposch, Riverside, Conn, assiguor t0 Pitney-Bowes, Inc., Stamford, Conn., a corporation of Delaware Filed Oct. 17, 1966, Ser. No. 587,303 6 Claims. (Cl. 230-118) This invention relates to an improved friction type fluid pump or compressor. More particularly the invention relates to an improved rotor construction and arrangement for a multiple disc type of frictional compressor.

-In a socalled Tesla pump, or a pump which has a rotor that includes a series of coaxially arranged friction discs, the rotor is driven at high rotative speeds so as to draw fluid into the pump through an inlet conduit near the center of the rotor and to angularly accelerate this fluid. The angular velocity and centrifugal forces thereby established cause the fluid to flow in a generally spiral path to an outlet conduit which in most cases extends tangentially from the rotor housing. In this type of device it is most important to keep the rotor mass as low as possible and to this end it has been proposed to make each rotor disc from a flexible material. Difficulty is encountered here when rotor discs are made too thin or flexible in that there is a tendency at high rotor speeds for the radially outer portions of the axially outer discs to axially flex toward the centermost ones of said discs. Too much of this type of flexing or axial collapse of the peripheral portion of the discs tends to reduce the efliciency of and the desired flow characteristics in a Tesla type compressor.

One object of the present invention is to provide an improved rotor construction and arrangement for a more practical and efficient Tesla type compressor.

Another object of the invention is to provide a novel axial spacing or distribution for the rotor friction discs of a Tesla type pump.

Another object of the invention is to provide a novel variation in the rigidity of the rotor friction discs of a Tesla type pump.

Another object of the invention is to provide a novel rotor construction and arrangement for a friction type compressor whereby a group of friction discs of different rigidity are axially spaced different distances apart.

Further objects will become apparent as the disclosure progresses.

In the drawings:

FIG. 1 is a partially cut away plan view of the instant apparatus.

FIG. 2 is a front elevational view in partial section of the apparatus of FIG. 1.

FIG. 3 is a partial sectional view taken along section line 3-3 of FIG. 1.

FIG. 4 is an enlarged fragmentary elevational view in partial section and illustrates the rotor hub construction.

FIG. 5 is a fragmentary plan view of the rotor hub arrangement.

FIGS. 6 and 7 are diagrammatic views illustrating two specific arrangements for the rotor discs of the instant pump.

Referring to FIGS. 1, 2 and 3 the present pumping device comprises a main body or housing 10 that includes a generally circular ring or frame member 11 and a pair of upper and lower housing plates 12 and 13. The ring 11 and plates 12 and 13 are mutually secured together by any suitable fastening means so as to form a substantially closed and generally flat circular rotor chamber 14, FIG. 3, in which a pump rotor 15 may be disposed. The upper surface of the housing plate 12 is formed with a generally radially extending groove 16 which partially defines a 3,400,883 Patented Sept. 10, 1968 fluid inlet passage as will be discussed below, while the ring or frame member 11 is provided with a generally tangentially disposed fluid outlet conduit 17 that conducts the pressurized fluid away to any suitably connected downstream conduit means such as is illustrated at 18 in FIG. 1. The radially inner walls of the ring 11 define a spiral as may be seen from FIG. 1, and the outlet conduit 17 effectively defines an exhaust diffuser.

A drive means 20, FIG. 2, is provided for rotating the rotor 15, this means comprising a box-like housing 21, FIG. 3, that includes an upper rectangular member 22 which is formed with a rectangular recess 23 and which has a plate 24 secured by any suitable means not shown to the lower side thereof. The drive housing 21 is received in a correspondingly shaped recess that is formed in the upper surface of the housing plate 12 to the same depth as said fluid inlet groove 16, said housing 21 being secured in this position by any suitable means, e.g. screws 25, FIG. 1. The lower surface of the plate 24 is also formed with a recess 26 that substantially has the same outer plan profile (as seen in FIG. 1) as that for said groove 16. A vertically disposed rotor shaft 30 is rotatably mounted in the drive housing 21 and has fixed thereto a pulley 31 which is operatively driven through a suitable belt 32 and a larger pulley 33, the latter being secured to the shaft of a motor 34. Motor 34 is fixed by any suitable means not shown to the top of the drive housing 21.

The rotor shaft 30 extends downwardly from the housing 21, through an enlarged aperture 35 formed in and through the said housing plate 12 and into the rotor chamber 14. Secured to the lower end of shaft 30 is the rotor 15, the latter comprising a hub 36, FIG. 4, which is fixed on the lower end of shaft 30 and which is provided with an upper flange 37. Eight thin flexible friction discs 40-47 inclusive having appropriate center apertures are mounted on said hub and are nominally maintained in axially spaced relation by washers or annular spacers 50. The discs and alternate spacers are axially clamped between the said hub flange 37 and a clamp washer 51 that is secured to the lower end of the hub 36 by suitable screws such as 52. The lower housing plate 13 is formed with a central recess 53, FIG. 3, to accommodate the clamp washer 51 and related parts. Each friction disc is formed with a plurality of suitable fluid inlet apertures such as 54 illustrated in FIG. 5, these apertures being respectively axially aligned so as to facilitate the proper entry of inlet fluid to the central regions of the rotor.

In the operation of the apparatus thus far described when motor 34 is operated so as to drive the rotor 15 at a high angular rate of speed fluid, such as air, is drawn in through the inlet passage that is cooperatively defined by the said grooves 16 and 26, around the lower bearing area for rotor shaft 30, through housing aperture 35 and finally through the aligned disc holes 54 to the radially inner spaces between the various discs 40-47. The rapidly rotating friction discs produce an angular acceleration of the said fluid between said discs and this angular motion causes the fluid to be centrifugally compressed and delivered under pressure to the outlet conduit means 17 and 18. As is expected a relatively low fluid pressure will exist near the center of the rotor, this condition causing inlet fluid to be drawn into the central regions of the rotor as above described. It will be noted that this inlet flow of fluid passes around the lower bearing boss 56 for the rotor shaft and in so doing produces a desirable cooling effect on this hearing area.

Either of two specific arrangements of the friction discs may be utilized to improve the operational characteristics of the pump, and these arrangements will now be described with reference to the diagrammatic sketches of FIG. 6 and 7. The first arrangement is illustrated in FIG. 6, the rotor in this case having eight discs 60-67, inclusive, that are preferably made from a plastic material, such as Mylar, and all have substantially the same axial thickness (for example .0075 inch). The axial dimensions of the spacers such as 50 are varied here so that the discs 60-67 are mutually spaced successively farther apart progressing from the centermost discs 63, 64 toward the outermost discs 60, 67 respectively. The amount of the relative variable spacing is denoted by the progression 2, 3, 4, 6, as indicated in FIG. 6; i.e. the distance between discs 63 and 64 is two units of length, the distance between discs 64 and 65 and between discs 62 and '63 is in each case three of said length units, the distance between discs 65 and 66 and between discs 61 and 62 is in each case four of said length units, and the distance between discs 66 and 67 and between discs 60 and 61 is in each case six of said length units. An exemplary value for one unit of length here is one sixteenth of an inch. The purpose for the variable disc spacing here is, inter alia, to compensate for the operational tendency for the radially outer regions of the discs to flex toward the said centermost discs of the rotor, this condition, which is illustrated in FIG. 2, existing by reason of the relatively higher static fluid pressures present between the outermost discs and the adjacent stationary walls of the cover plates 12 and 13. Thus by utilizing the disc spacing of FIG. 6 the effective distances between the various discs tend to become more uniform during high speed rotation and hence the discs will be more uniformly operationally loaded in accelerating the fluid therebetween.

The second rotor arrangement is illustrated in FIG. 7 and in this case the rotor is provided with eight discs 70-77 inclusive, these discs again being made of a plastic material such as Mylar and being mounted on the rotor hub 36 in the same manner as that discussed above in connection with FIGS. 4-6. Here the same 2, 3, 4, 6 disc spacing as was described in connection with FIG. 6 is utilized, and in addition a variation in the axial thickness and hence rigidity of these discs is introduced. The six inside discs 71-76 are relatively thin (their axial thickness may for example be .005 inch) while the outer discs 70 and 77 are relatively thick (for example .010 inch). By thus increasing the rigidity as well as increasing the axial spacing of the outer discs of the rotor a further improvement in rotor efficiency may be obtained by reason of an overall decrease in the mass of the rotor while giving greater rigidity and strength and thus stability to those axially outer discs which are subject to greatest axial flexing stresses. This particular rotor arrangement has been found to afford excellent performance characteristics over long periods of use.

Since many changes could be made in the embodiments of the invention as particularly described and shown herein without departing from the scope of the invention, it is intended that these embodiments be considered as exemplary and that the invention not be limited except as warranted by the following claims.

What is claimed is:

1. In a friction type compressor: having a housing;

a main shaft rotatably mounted in said housing; and

drive means for rotating said shaft:

the improvement comprising a plurality of friction discs carried by said shaft and disposed with said housing, said discs being mutual spaced progressively farther axial distances apart;

said discs varying in thickness and rigidity with the two axially outermost ones of said discs being thicker and more rigid than the axially inner ones of said discs.

2. In a friction type compressor: having a housing;

a main shaft rotatably mounted in said housing; and

drive means for rotating said shaft:

the improvement comprising a plurality of flexible discs secured to said shaft, some of said discs being more rigid than others of said discs and the axial spacing between said discs being varied; and

conduit means for conducting inlet fluid past at least a portion of the bearing means for said shafts; and

said discs varying in thickness and rigidity with the two axially outermost ones of said discs being thicker and more rigid than the axially inner ones of said discs.

3. In a friction type compressor: having a housing mounted on said frame;

a main shaft mounted for rotation within said housing;

said housing being provided with fluid inlet and outlet passages; and

drive means for rotating said main shaft;

the improvement comprising a plurality of axially spaced flexible discs mounted for rotation with said main shaft, the axially outer ones of said discs being axially more rigid than the axially inner ones of said flexible discs;

said discs being variably spaced in a substantially 2-3-4-6 axial distance relation from an inner to an outer disc.

4. Apparatus as defined by claim 3 wherein the said variable spacing extends in both axial directions from the center ones of said discs.

5. Apparatus as defined by claim 4 wherein the outer discs are more rigid than the inner discs.

6. Apparatus as defined by claim 5 wherein said discs are made of plastic material, and the thickness of outer discs is in the order of .010 inch while the thickness of the inner discs is in the order of .005 inch.

References Cited UNITED STATES PATENTS 1,061,142 5/1913 Tesla 103-84 2,626,135 1/ 1953 Serner. 2,706,016 4/ 1955 Schlumbohm 230-1 1 8 2,632,598 3/1953 Wales 230-133 FOREIGN PATENTS 439,542 4/ 1912 France. 452,393 3/1913 France.

4,036 1910 Great Britain.

HENRY F. RADUAZO, Primary Examiner. 

1. IN A FRICTION TYPE COMPRESSOR: HAVING A HOUSING; A MAIN SHAFT ROTATABLY MOUNTED IN SAID HOUSING; AND DRIVE MEANS FOR ROTATING SAID SHAFT: THE IMPROVEMENT COMPRISING A PLURALITY OF FRICTION DISCS CARRIED BY SAID SHAFT AND DISPOSED WITH SAID HOUSING, SAID DISCS BEING MUTUAL SPACED PROGRESSIVELY FARTHER AXIAL DISTANCES APART; SAID DISCS VARYING IN THICKNESS AND RIGIDITY WITH THE TWO AXIALLY OUTERMOST ONES OF SAID DISCS BEING THICKER AND MORE RIGID THAN THE AXIALLY INNER ONES OF SAID DISCS. 